Siberian smoke over Oklahoma as seen from Twin Otter on May 27, 2003

Photo courtesy of Roy Woods

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Aerosol Extinction (1/km)

Alt

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Neph+PSAP (453 nm) 18:34-18:52 UT

How well can we measure the vertical profile of tropospheric aerosol extinction?

B. Schmid, R. Ferrare, C. Flynn, R. Elleman, D. Covert, A. Strawa, E. Welton, D. Turner,H. Jonsson, J. Redemann, J. Eilers, K. Ricci, A. Hallar, M. Clayton, J. Michalsky, A. Smirnov, B. Holben, J. Barnard

Paper submitted to AIOP JGR special issue, Feb 3, 2005

Focus on data obtained in vertical profiles over SGP CF

Altitudes: ~90 – 5600 m

CIRPAS Twin OtterARM Aerosol IOP – May 2003

Photo courtesy Yin-Nan Lee, BNL

How do we measure the vertical profile of aerosol extinction?

unaltered aerosol @ ambient concentration @ thermodynamic state

Airborne:• Nephelometer+PSAP• Cavity-Ring-Down (Cadenza) • Sunphotometry (AATS-14)

Ground based:• Raman Lidar (CARL)• MPLNET• MPLARM

NASA Ames Airborne Tracking SunphotometerAATS-14: 354-2139 nm

Aerosol Optical Depth and H2O columnAerosol Extinction and H2O density in suitable profiles

x y # profiles # data points

AATS-14 Neph+PSAP 26 3484AATS-14 Cadenza 26 2856

AATS-14 MPLNET 2.0 13 587AATS-14 MPLARM 19 2073

AATS-14 Raman Lidar 11 468

AATS-14 in-situ H2O 35 6705

Summary of AIOP Extinction ComparisonsRaman

Neph+PSAP

MPLNET

Cadenza

CadenzaNeph+PSAP

MPLARM

Neph+PSAP

-50%

-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50%

Re

l. B

ias

to

AA

TS

-14

= 354 nm

= 453 nm

= 519 nm

= 675 nm = 1550 nm

Extinction comparisons in previous field campaigns

TARFOX, 1996

ACE-2, 1997

PRIDE, 2000

SAFARI, 2000

ACE-Asia, 2001

ARM Aerosol IOP, 2003

CLAMS, 2001

Conclusions: Current Effort

• Looking at results from 6 field campaigns, airborne in-situ measurements of extinction tend to be biased slightly low (mean of 17%) when compared to airborne sunphotometer extinction.

• Lidar measurements of extinction from 6 field campaigns show no or positive biases.

• Systematic errors in measuring ambient aerosol extinction profiles with current state-of-the-art instrumentation are 15-20% in the visible. Random errors are considerably larger.

• Raman Lidar measurements in AIOP biased high (29 Mm-1 UV 54%). We expect better agreement from a “healthier” Raman lidar.

Summary of Achievements: Current ARM ST EffortVertically resolved aerosol optical properties over the ARM SGP site

PI: Schmid, Co-I: Pilewskie, Strawa, Russell, Bergstrom, Redemann

• PI instrumental in planning and executing AIOP. Platform Scientist Twin Otter.

• Twin Otter data used in 10 publications for AIOP JGR special issue.

• PI and Co-I’s have contributed directly to 7 of the 10 publications:

o Aerosol Indirect Effect Studies at Southern Great Plains during the May 2003 Intensive Operations Period. Feingold et al. (with Pilewskie).

o Comparison of methods for deriving aerosol asymmetry parameter. Andrews et al. (with Schmid)

o Evaluation of Daytime Measurements of Aerosols and Water Vapor made by an Operational Raman Lidar over the Southern Great Plains. Ferrare et al. (with Schmid, Redemann),

o How well can we measure the vertical profile of aerosol extinction? Schmid et al. (with Strawa, Redemann)

o A comparison of aerosol optical properties obtained from in-situ measurements and retrieved from Sun and sky radiance observations during the May 2003 ARM aerosol intensive observation period. Ricchiazzi et al. (with Schmid)

o Comparison of In-Situ and Remote Aerosol Optical Property Measurements During the DOE Aerosol IOP. Strawa et al. (with Schmid), close to submission,

o Elevated injection height, long-range transport, and evolution of a Siberian forest fire smoke plume. Colarco et al. (with Schmid) close to submission

Photo courtesy Yin-Nan Lee, BNL

CRF Raman Lidar, since 1997Unattended, 24/7, H2O, aerosolsGoal: 10 yr CDR

Aerosol Extinction profiles =355 nm Unnoticed loss of sensitivity leading up to AIOP Automated algorithms had to be modified to reduce impact of

sensitivity loss, but 54% bias remains Major upgrades/mods were performed after AIOP resulting in

significantly better performance than during any other time.

•Aerosol Extinction profiles =523 nm are a new product in -stage (C. Flynn)

•First validation in AIOP over SGP

•Would like larger dataset for validation

Micro Pulse Lidars

Deployed at:•SGP •NSA (pol.)•AMF (pol.)•TWP Manus•TWP Nauru•TWP Darwin •& several spares

Proposed SGP Lidar Validation IOPGoal: Validate CARL, MPL and IAP Aerosol Extinction Profiles

• AATS-14 aboard a profiling aircraft• 10 days, 20 flight hours• Profiles 300 – 23,000 ft altitude• Sep 2005, IOP (after NASA CALIPSO validation experiment)

Dec. 10, 2004 Endorsed by AWG Feb. 28, 2005 Pre-proposal submitted Mar. 18, 2005 (?) Pre-proposal approved

AATS-14 on Sky Research J-31

Proposed future ST effortsTask 1:

Aerosol Best Estimate (ABE) Product – Sensitivity Study• Aerosol extinction, o, g at all times and heights above all ACRF

• Inputs for BBHRP & Shortwave QME• Currently for SGP only• How much detail is required? (varies by site? use of resources)• Collaborators (Turner, Ferrare, Mlawer)

Proposed future ST effortsTask 2:

Vertically resolved aerosol and cloud radiative properties over SGP• Radiometric AIOP aircraft data set underused• Observation-based quantification of effect of aerosol & clouds on radiation• Radiative closure (in-situ RTM radiation)• BBHRP test cases• Collaborators: Pilewskie, Mlawer

CM22 SSFR CG4

Proposed future ST effortsTask 3:

• Integrated analysis of data from proposed Lidar Validation IOP (if approved before submission of full ST proposal)

• Collaborators: Ferrare, Turner, Flynn